First up, i want to safely remove the nvidia driver before updating the system, everytime ive tried "updating" drivers it hasnt usually gone to well with other gentoo based distro's ( its prob just an error im making )

But basically i want to remove version 295 nvidia drivers. and install 302.17, with nvidia-settings.

Second

Does mirror select work with sabayon or is there another way to select mirrors for quicker downloads in the australian region

I don't know what you are trying to archive by removing nvidia driver first. You could do it by killing the xserver and login in a login shell. From there you could use the equo command to remove and install nvidia-drivers and then reboot.

Personally I updated my drivers through the normal process and never ran into problems.

it will automatically upgrade and install latest nvidia-drivers, matching the kernel you're currently running.Unless you recently switched to a new kernel, and the old nvidia-drivers were installed for the old kernel.In that case, if you don't use that kernel anymore, you can safely remove/purge the old driver.You might want to remove the old kernel as well.And, like Jomiel said:if you want a mrror in your direct neighbourhood, you can sort the mirrors.You can do so as root on the commandline:for daily repository;

kernel changes must be done by user with kernel-switcher. We avoid kernel upgrades in regular updates as it confuses people too much. kernel-switcher will update the kernel and all its drivers/modules for that kernel

If you're happy with the current kernel, and everything is working as it should, you can stick to that kernel.However, if a new kernel comes available, and like to try you can install using kernel-switcher.Kernel-switcher also installs all correct drivers for that kernel. (nvidia, ati, VirtualBox-modules, etc...)A new menu entry will be created in Grub., so you can always choose on boot, which kernel you wish to boot from.